U.S. patent number 11,117,465 [Application Number 16/137,846] was granted by the patent office on 2021-09-14 for vehicle driving-force distributing device.
This patent grant is currently assigned to TOYOTA JIDOSHA KABUSHIKI KAISHA. The grantee listed for this patent is TOYOTA JIDOSHA KABUSHIKI KAISHA. Invention is credited to Masayuki Hashimoto, Ryota Horie, Masaya Michishita, Takahiro Yoshimura.
United States Patent |
11,117,465 |
Yoshimura , et al. |
September 14, 2021 |
Vehicle driving-force distributing device
Abstract
A vehicle driving-force distributing device includes: first
connecting/disconnecting teeth disposed on the inner
circumferential side of the ring gear; a connecting/disconnecting
mechanism that includes a cylindrical member and a
connecting/disconnecting sleeve including second
connecting/disconnecting teeth and spline-fitted movably in the
rotation axis direction and relatively non-rotatably to the outer
circumferential side of the shaft insertion portion and that
connects and disconnects a power transmission path between the ring
gear and the differential case by moving the
connecting/disconnecting sleeve in the rotation axis direction
between a meshing position at which the second
connecting/disconnecting teeth are meshed with the first
connecting/disconnecting teeth and a non-meshing position at which
the second connecting/disconnecting teeth are not meshed with the
first connecting/disconnecting teeth; and a synchronizing mechanism
disposed between the ring gear and the cylindrical member and
reducing a relative rotation between the first
connecting/disconnecting teeth and the second
connecting/disconnecting teeth.
Inventors: |
Yoshimura; Takahiro (Toyota,
JP), Michishita; Masaya (Okazaki, JP),
Horie; Ryota (Nagoya, JP), Hashimoto; Masayuki
(Nagoya, JP) |
Applicant: |
Name |
City |
State |
Country |
Type |
TOYOTA JIDOSHA KABUSHIKI KAISHA |
Toyota |
N/A |
JP |
|
|
Assignee: |
TOYOTA JIDOSHA KABUSHIKI KAISHA
(Toyota, JP)
|
Family
ID: |
1000005801250 |
Appl.
No.: |
16/137,846 |
Filed: |
September 21, 2018 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20190092166 A1 |
Mar 28, 2019 |
|
Foreign Application Priority Data
|
|
|
|
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Sep 25, 2017 [JP] |
|
|
JP2017-184221 |
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F16H
48/20 (20130101); B60K 17/3462 (20130101); B60K
17/02 (20130101); B60K 17/344 (20130101); B60K
17/165 (20130101); B60K 23/0808 (20130101); F16H
48/08 (20130101); B60K 2023/0833 (20130101); B60K
2023/0858 (20130101) |
Current International
Class: |
B60K
17/346 (20060101); B60K 17/16 (20060101); F16H
48/08 (20060101); B60K 23/08 (20060101); F16H
48/20 (20120101); B60K 17/02 (20060101); B60K
17/344 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
105501058 |
|
Apr 2016 |
|
CN |
|
2016-074370 |
|
May 2016 |
|
JP |
|
2016-168982 |
|
Sep 2016 |
|
JP |
|
2016-203875 |
|
Dec 2016 |
|
JP |
|
Primary Examiner: Holmes; Justin
Attorney, Agent or Firm: Oliff PLC
Claims
What is claimed is:
1. A vehicle driving-force distributing device including a ring
gear disposed rotatably around a rotation axis and a differential
device disposed rotatably around the rotation axis and including a
differential case in which a pair of differential gears is
assembled, the vehicle driving-force distributing device
distributing a driving force transmitted from a drive power source
to the ring gear through the differential device to left and right
drive wheels, comprising: first connecting/disconnecting teeth
disposed on the inner circumferential side of the ring gear; a
connecting/disconnecting mechanism that includes a cylindrical
member arranged concentrically with the differential gears and
coupled relatively non-rotatably to a shaft insertion portion at
one end portion of the differential case and a
connecting/disconnecting sleeve including second
connecting/disconnecting teeth on the outer circumferential side
and spline-fitted movably in the rotation axis direction and
relatively non-rotatably to the outer circumferential side of the
shaft insertion portion and that connects and disconnects a power
transmission path between the ring gear and the differential case
by moving the connecting/disconnecting sleeve in the rotation axis
direction between a meshing position at which the second
connecting/disconnecting teeth are meshed with the first
connecting/disconnecting teeth and a non-meshing position at which
the second connecting/disconnecting teeth are not meshed with the
first connecting/disconnecting teeth; and a synchronizing mechanism
disposed between the ring gear and the cylindrical member and
reducing a relative rotation between the first
connecting/disconnecting teeth and the second
connecting/disconnecting teeth, wherein: the
connecting/disconnecting sleeve includes inner-circumferential
spline teeth for spline fitting to the outer circumferential side
of the shaft insertion portion, the pitch circle of the second
connecting/disconnecting teeth disposed on the outer
circumferential surface of the connecting/disconnecting sleeve has
a larger diameter than the pitch circle of the
inner-circumferential spline teeth, and the second
connecting/disconnecting teeth disposed on the outer
circumferential side of the connecting/disconnecting sleeve have a
face width smaller than the face width of the inner-circumferential
spline teeth.
2. The vehicle driving-force distributing device according to claim
1, wherein the shaft insertion portion and the cylindrical member
have the outer and inner diameters equal to each other, and wherein
the shaft insertion portion and the cylindrical member are lined up
and coupled to each other by a tubular coupling member having a
smaller diameter than the outer diameter of the shaft insertion
portion and the cylindrical member and fitted into the shaft
insertion portion and the cylindrical member.
3. The vehicle driving-force distributing device according to claim
1, wherein the synchronizing mechanism includes a friction
engagement member that includes on the outer circumferential side a
second tapered friction engagement surface selectively frictionally
engaged with a first tapered friction engagement surface formed on
the inner circumferential surface of the ring gear and that is
spline-fitted movably in the rotation axis direction and relatively
non-rotatably to the outer circumferential side of the cylindrical
member to move in the rotation axis direction together with the
connecting/disconnecting sleeve, and the synchronizing mechanism
reduces a relative rotation between the first
connecting/disconnecting teeth and the second
connecting/disconnecting teeth through a frictional engagement
between the first tapered friction engagement surface and the
second tapered friction engagement surface at the non-meshing
position.
4. The vehicle driving-force distributing device according to claim
2, wherein the synchronizing mechanism includes a friction
engagement member that includes on the outer circumferential side a
second tapered friction engagement surface selectively frictionally
engaged with a first tapered friction engagement surface formed on
the inner circumferential surface of the ring gear and that is
spline-fitted movably in the rotation axis direction and relatively
non-rotatably to the outer circumferential side of the cylindrical
member to move in the rotation axis direction together with the
connecting/disconnecting sleeve, and the synchronizing mechanism
reduces a relative rotation between the first
connecting/disconnecting teeth and the second
connecting/disconnecting teeth through a frictional engagement
between the first tapered friction engagement surface and the
second tapered friction engagement surface at the non-meshing
position.
5. The vehicle driving-force distributing device according to claim
3, wherein the connecting/disconnecting mechanism includes an
actuator and a latching mechanism, and wherein the latching
mechanism includes a first piston reciprocated in the rotation axis
direction in accordance with an on/off operation of the actuator, a
second piston disposed movably in the rotation axis direction on
the outer circumferential side of the cylindrical member and driven
by the first piston in the rotation axis direction to press the
friction engagement member and the connecting/disconnecting sleeve,
a spring urging the second piston in the backward movement
direction, and a holder latching the second piston against the
urging force of the spring in accordance with reciprocation of the
first piston and unlatching the second piston in accordance with
reciprocation of the first piston to allow the second piston to
move backward in accordance with the urging force of the
spring.
6. The vehicle driving-force distributing device according to claim
4, wherein the connecting/disconnecting mechanism includes an
actuator and a latching mechanism, and wherein the latching
mechanism includes a first piston reciprocated in the rotation axis
direction in accordance with an on/off operation of the actuator, a
second piston disposed movably in the rotation axis direction on
the outer circumferential side of the cylindrical member and driven
by the first piston in the rotation axis direction to press the
friction engagement member and the connecting/disconnecting sleeve,
a spring urging the second piston in the backward movement
direction, and a holder latching the second piston against the
urging force of the spring in accordance with reciprocation of the
first piston and unlatching the second piston in accordance with
reciprocation of the first piston to allow the second piston to
move backward in accordance with the urging force of the
spring.
7. A vehicle driving-force distributing device including a ring
gear disposed rotatably around a rotation axis and a differential
device disposed rotatably around the rotation axis and including a
differential case in which a pair of differential gears is
assembled, the vehicle driving-force distributing device
distributing a driving force transmitted from a drive power source
to the ring gear through the differential device to left and right
drive wheels, comprising: first connecting/disconnecting teeth
disposed on the inner circumferential side of the ring gear; a
connecting/disconnecting mechanism that includes a cylindrical
member arranged concentrically with the differential gears and
coupled relatively non-rotatably to a shaft insertion portion at
one end portion of the differential case and a
connecting/disconnecting sleeve including second
connecting/disconnecting teeth on the outer circumferential side
and spline-fitted movably in the rotation axis direction and
relatively non-rotatably to the outer circumferential side of the
shaft insertion portion and that connects and disconnects a power
transmission path between the ring gear and the differential case
by moving the connecting/disconnecting sleeve in the rotation axis
direction between a meshing position at which the second
connecting/disconnecting teeth are meshed with the first
connecting/disconnecting teeth and a non-meshing position at which
the second connecting/disconnecting teeth are not meshed with the
first connecting/disconnecting teeth; and a synchronizing mechanism
disposed between the ring gear and the cylindrical member and
reducing a relative rotation between the first
connecting/disconnecting teeth and the second
connecting/disconnecting teeth, wherein the shaft insertion portion
and the cylindrical member have the outer and inner diameters equal
to each other, and wherein the shaft insertion portion and the
cylindrical member are lined up and coupled to each other by a
tubular coupling member having a smaller diameter than the outer
diameter of the shaft insertion portion and the cylindrical member
and fitted into the shaft insertion portion and the cylindrical
member.
8. The vehicle driving-force distributing device according to claim
7, wherein the synchronizing mechanism includes a friction
engagement member that includes on the outer circumferential side a
second tapered friction engagement surface selectively frictionally
engaged with a first tapered friction engagement surface formed on
the inner circumferential surface of the ring gear and that is
spline-fitted movably in the rotation axis direction and relatively
non-rotatably to the outer circumferential side of the cylindrical
member to move in the rotation axis direction together with the
connecting/disconnecting sleeve, and the synchronizing mechanism
reduces a relative rotation between the first
connecting/disconnecting teeth and the second
connecting/disconnecting teeth through a frictional engagement
between the first tapered friction engagement surface and the
second tapered friction engagement surface at the non-meshing
position.
9. The vehicle driving-force distributing device according to claim
8, wherein the connecting/disconnecting mechanism includes an
actuator and a latching mechanism, and wherein the latching
mechanism includes a first piston reciprocated in the rotation axis
direction in accordance with an on/off operation of the actuator, a
second piston disposed movably in the rotation axis direction on
the outer circumferential side of the cylindrical member and driven
by the first piston in the rotation axis direction to press the
friction engagement member and the connecting/disconnecting sleeve,
a spring urging the second piston in the backward movement
direction, and a holder latching the second piston against the
urging force of the spring in accordance with reciprocation of the
first piston and unlatching the second piston in accordance with
reciprocation of the first piston to allow the second piston to
move backward in accordance with the urging force of the
spring.
10. A vehicle driving-force distributing device including a ring
gear disposed rotatably around a rotation axis and a differential
device disposed rotatably around the rotation axis and including a
differential case in which a pair of differential gears is
assembled, the vehicle driving-force distributing device
distributing a driving force transmitted from a drive power source
to the ring gear through the differential device to left and right
drive wheels, comprising: first connecting/disconnecting teeth
disposed on the inner circumferential side of the ring gear; a
connecting/disconnecting mechanism that includes a cylindrical
member arranged concentrically with the differential gears and
coupled relatively non-rotatably to a shaft insertion portion at
one end portion of the differential case and a
connecting/disconnecting sleeve including second
connecting/disconnecting teeth on the outer circumferential side
and spline-fitted movably in the rotation axis direction and
relatively non-rotatably to the outer circumferential side of the
shaft insertion portion and that connects and disconnects a power
transmission path between the ring gear and the differential case
by moving the connecting/disconnecting sleeve in the rotation axis
direction between a meshing position at which the second
connecting/disconnecting teeth are meshed with the first
connecting/disconnecting teeth and a non-meshing position at which
the second connecting/disconnecting teeth are not meshed with the
first connecting/disconnecting teeth; and a synchronizing mechanism
disposed between the ring gear and the cylindrical member and
reducing a relative rotation between the first
connecting/disconnecting teeth and the second
connecting/disconnecting teeth, wherein: the
connecting/disconnecting sleeve includes inner-circumferential
spline teeth for spline fitting to the outer circumferential side
of the shaft insertion portion, the pitch circle of the second
connecting/disconnecting teeth disposed on the outer
circumferential surface of the connecting/disconnecting sleeve has
a larger diameter than the pitch circle of the
inner-circumferential spline teeth, the shaft insertion portion and
the cylindrical member have the outer and inner diameters equal to
each other, and the shaft insertion portion and the cylindrical
member are lined up and coupled to each other by a tubular coupling
member having a smaller diameter than the outer diameter of the
shaft insertion portion and the cylindrical member and fitted into
the shaft insertion portion and the cylindrical member.
11. The vehicle driving-force distributing device according to
claim 10, wherein the synchronizing mechanism includes a friction
engagement member that includes on the outer circumferential side a
second tapered friction engagement surface selectively frictionally
engaged with a first tapered friction engagement surface formed on
the inner circumferential surface of the ring gear and that is
spline-fitted movably in the rotation axis direction and relatively
non-rotatably to the outer circumferential side of the cylindrical
member to move in the rotation axis direction together with the
connecting/disconnecting sleeve, and the synchronizing mechanism
reduces a relative rotation between the first
connecting/disconnecting teeth and the second
connecting/disconnecting teeth through a frictional engagement
between the first tapered friction engagement surface and the
second tapered friction engagement surface at the non-meshing
position.
12. The vehicle driving-force distributing device according to
claim 11, wherein the connecting/disconnecting mechanism includes
an actuator and a latching mechanism, and wherein the latching
mechanism includes a first piston reciprocated in the rotation axis
direction in accordance with an on/off operation of the actuator, a
second piston disposed movably in the rotation axis direction on
the outer circumferential side of the cylindrical member and driven
by the first piston in the rotation axis direction to press the
friction engagement member and the connecting/disconnecting sleeve,
a spring urging the second piston in the backward movement
direction, and a holder latching the second piston against the
urging force of the spring in accordance with reciprocation of the
first piston and unlatching the second piston in accordance with
reciprocation of the first piston to allow the second piston to
move backward in accordance with the urging force of the spring.
Description
This application claims priority from Japanese Patent Application
No. 2017-184221 filed on Sep. 25, 2017, the disclosure of which is
herein incorporated by reference in its entirety.
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention relates to a vehicle driving-force
distributing device distributing a driving force transmitted from a
drive power source via a differential mechanism to left and right
drive wheels and, more particularly, to a technique of increasing
strength of first and second connecting/disconnecting teeth used in
a connecting/disconnecting mechanism to improve durability
thereof.
Description of the Related Art
A known vehicle driving-force distributing device includes (a) a
ring gear disposed rotatably around a rotation axis due to a
driving force transmitted from a drive power source; (b) a
differential device having a differential case in which a pair of
differential gears is assembled; (c) a cylindrical rotating body
having first connecting/disconnecting teeth on an outer
circumferential side, disposed on one end side of the differential
case and rotating around the rotation axis together with the
differential case; a connecting/disconnecting mechanism having
second connecting/disconnecting teeth engageable with the first
connecting/disconnecting teeth on an inner circumferential side,
including a connecting/disconnecting sleeve spline-fitted to the
inner circumferential side of the ring gear relatively movably in a
rotation axis direction, and connecting/disconnecting a power
transmission path between the ring gear and the differential case
by moving the connecting/disconnecting sleeve between a meshing
position at which the second connecting/disconnecting teeth are
meshed with the first connecting/disconnecting teeth and a
non-meshing position at which the second connecting/disconnecting
teeth are not meshed with the first connecting/disconnecting teeth;
and a synchronizing mechanism disposed between the
connecting/disconnecting sleeve and the cylindrical rotating body
and reducing relative rotation between the first
connecting/disconnecting teeth and the second
connecting/disconnecting teeth before meshing of the first
connecting/disconnecting teeth and the second
connecting/disconnecting teeth, and distributes a driving force
transmitted from a drive power source through the meshing of the
first connecting/disconnecting teeth and the second
connecting/disconnecting teeth via the differential device to left
and right drive wheels. For example, this corresponds to a vehicle
driving-force distributing device described in Patent Document
1.
CITATION LIST
Patent Document 1: Japanese Laid-Open Patent Publication No.
2016-203875
SUMMARY OF THE INVENTION
Technical Problem
The vehicle driving-force distributing device as described in
Patent Document 1 has the second connecting/disconnecting teeth
formed on the inner circumferential side of the
connecting/disconnecting sleeve spline-fitted to the inner
circumferential side of the ring gear and moves the
connecting/disconnecting sleeve in the rotation axis direction
between the meshing position at which the second
connecting/disconnecting teeth are meshed with the first
connecting/disconnecting teeth and the non-meshing position at
which the second connecting/disconnecting teeth are not meshed with
the first connecting/disconnecting teeth to connect/disconnect the
power transmission path between the ring gear and the differential
case. However, the second connecting/disconnecting teeth disposed
on the inner circumferential side of the connecting/disconnecting
sleeve for the purpose of power transmission and the first
connecting/disconnecting teeth meshed therewith have diameter
dimensions limited due to being disposed on the inner
circumferential side as compared to spline teeth for spline fitting
disposed on the outer circumferential side of the
connecting/disconnecting sleeve, and therefore have a problem of
being disadvantageous in terms of tooth strength.
The present invention was conceived in view of the situations and
it is therefore an object of the present invention to provide a
vehicle driving-force distributing device in which the first
connecting/disconnecting teeth and the second
connecting/disconnecting teeth used for the
connecting/disconnecting mechanism are advantageous in terms of
strength.
Solution to Problem
To achieve the above object, a first aspect of the present
invention provides a vehicle driving-force distributing device
including (a) a ring gear disposed rotatably around a rotation axis
and a differential device disposed rotatably around the rotation
axis and including a differential case in which a pair of
differential gears is assembled, the vehicle driving-force
distributing device distributing a driving force transmitted from a
drive power source to the ring gear through the differential device
to left and right drive wheels, comprising: (b) first
connecting/disconnecting teeth disposed on the inner
circumferential side of the ring gear; (c) a
connecting/disconnecting mechanism that includes a cylindrical
member arranged concentrically with the differential gears and
coupled relatively non-rotatably to a shaft insertion portion at
one end portion of the differential case and a
connecting/disconnecting sleeve including second
connecting/disconnecting teeth on the outer circumferential side
and spline-fitted movably in the rotation axis direction and
relatively non-rotatably to the outer circumferential side of the
shaft insertion portion and that connects and disconnects a power
transmission path between the ring gear and the differential case
by moving the connecting/disconnecting sleeve in the rotation axis
direction between a meshing position at which the second
connecting/disconnecting teeth are meshed with the first
connecting/disconnecting teeth and a non-meshing position at which
the second connecting/disconnecting teeth are not meshed with the
first connecting/disconnecting teeth; and (d) a synchronizing
mechanism disposed between the ring gear and the cylindrical member
and reducing a relative rotation between the first
connecting/disconnecting teeth and the second
connecting/disconnecting teeth.
A second aspect of the present invention provides the vehicle
driving-force distributing device wherein the
connecting/disconnecting sleeve includes inner-circumferential
spline teeth for spline fitting to the outer circumferential side
of the shaft insertion portion, and wherein the pitch circle of the
second connecting/disconnecting teeth disposed on the outer
circumferential surface of the connecting/disconnecting sleeve has
a larger diameter than the pitch circle of the
inner-circumferential spline teeth.
A third aspect of the present invention provides the vehicle
driving-force distributing device wherein the second
connecting/disconnecting teeth disposed on the outer
circumferential side of the connecting/disconnecting sleeve have a
face width smaller than the face width of the inner-circumferential
spline teeth.
A fourth aspect of the present invention provides the vehicle
driving-force distributing device wherein the shaft insertion
portion and the cylindrical member have the outer and inner
diameters equal to each other, and wherein the shaft insertion
portion and the cylindrical member are lined up and coupled to each
other by a tubular coupling member having a smaller diameter than
the outer diameter of the shaft insertion portion and the
cylindrical member and fitted into the shaft insertion portion and
the cylindrical member.
A fifth aspect of the present invention provides the vehicle
driving-force distributing device wherein the synchronizing
mechanism includes a friction engagement member that includes on
the outer circumferential side a second tapered friction engagement
surface frictionally engaged with a first tapered friction
engagement surface formed on the inner circumferential surface of
the ring gear and that is spline-fitted movably in the rotation
axis direction and relatively non-rotatably to the outer
circumferential side of the cylindrical member to move in the
rotation axis direction together with the connecting/disconnecting
sleeve, and the synchronizing mechanism reduces a relative rotation
between the first connecting/disconnecting teeth and the second
connecting/disconnecting teeth through a frictional engagement
between the first tapered friction engagement surface and the
second tapered friction engagement surface at the non-meshing
position.
A sixth aspect of the present invention provides the vehicle
driving-force distributing device wherein the
connecting/disconnecting mechanism includes an actuator and a
latching mechanism, and wherein the latching mechanism includes a
first piston reciprocated in the rotation axis direction in
accordance with an on/off operation of the actuator, a second
piston disposed movably in the rotation axis direction on the outer
circumferential side of the cylindrical member and driven by the
first piston in the rotation axis direction to press the friction
engagement member and the connecting/disconnecting sleeve, a spring
urging the second piston in the backward movement direction, and a
holder latching the second piston against the urging force of the
spring in accordance with reciprocation of the first piston and
unlatching the second piston in accordance with reciprocation of
the first piston to allow the second piston to move backward in
accordance with the urging force of the spring.
Advantageous Effects of the Invention
The vehicle driving-force distributing device recited in the first
aspect of the invention includes: the connecting/disconnecting
sleeve having the second connecting/disconnecting teeth on the
outer circumferential side and spline-fitted movably in the
rotation axis direction and relatively non-rotatably to the outer
circumferential side of the shaft insertion portion; and the
synchronizing mechanism disposed between the ring gear and the
cylindrical member and reducing the relative rotation between the
second connecting/disconnecting teeth and the first
connecting/disconnecting teeth, and therefore, the second
connecting/disconnecting teeth disposed on the outer
circumferential side of the connecting/disconnecting sleeve have a
larger diameter than the spline teeth for spline fitting disposed
on the inner circumferential side of the connecting/disconnecting
sleeve. Therefore, the second connecting/disconnecting teeth and
the first connecting/disconnecting teeth meshed therewith can be
improved in strength, and thus, even if the space is limited due to
inclusion of the synchronizing mechanism, the vehicle driving-force
distributing device can be made advantageous in terms of the
strength of the first connecting/disconnecting teeth and the second
connecting/disconnecting teeth, so that the first
connecting/disconnecting teeth and the second
connecting/disconnecting teeth can be enhanced in durability.
Additionally, the synchronizing mechanism is disposed in a space
between the ring gear and the cylindrical member so that the
driving force is transmitted between the connecting/disconnecting
sleeve and the shaft insertion portion, and therefore, for example,
as compared to the case that both the cylindrical member and the
shaft insertion portion must be enhanced in strength if the driving
force is transmitted between the connecting/disconnecting sleeve
and the cylindrical member, the strength is advantageously enhanced
by increasing only the strength of the shaft insertion portion.
According to the vehicle driving-force distributing device recited
in the second aspect of the invention, the connecting/disconnecting
sleeve has the inner-circumferential spline teeth for spline
fitting to the outer circumferential side of the shaft insertion
portion, and the pitch circle of the second
connecting/disconnecting teeth disposed on the outer
circumferential surface of the connecting/disconnecting sleeve has
a larger diameter than the pitch circle of the
inner-circumferential spline teeth. As a result, the second
connecting/disconnecting teeth and the first
connecting/disconnecting teeth meshed therewith can be improved in
strength, and even if the space is limited due to disposition of
the synchronizing mechanism, the vehicle driving-force distributing
device can be made advantageous in terms of the strength of the
second connecting/disconnecting teeth and the first
connecting/disconnecting teeth.
According to the vehicle driving-force distributing device recited
in the third aspect of the invention, the second
connecting/disconnecting teeth disposed on the outer
circumferential side of the connecting/disconnecting sleeve have a
face width smaller than the face width of the inner-circumferential
spline teeth. As a result, the reciprocating stroke of the
connecting/disconnecting sleeve can be reduced. Therefore, the
vehicle driving-force distributing device can be made smaller in
the dimension in the rotation axis direction.
According to the vehicle driving-force distributing device recited
in the fourth aspect of the invention, the shaft insertion portion
and the cylindrical member have the outer and inner diameters equal
to each other, and the shaft insertion portion and the cylindrical
member are lined up and relatively non-rotatably coupled to each
other by the tubular coupling member having a smaller diameter than
the outer diameter of the shaft insertion portion and the
cylindrical member and fitted into the shaft insertion portion and
the cylindrical member. As a result, the radial dimension of the
vehicle driving-force distributing device is further reduced.
According to the vehicle driving-force distributing device recited
in the fifth aspect of the invention, the synchronizing mechanism
includes the friction engagement member that has on the outer
circumferential side the second tapered friction engagement surface
frictionally engageable with the first tapered friction engagement
surface formed on the inner circumferential surface of the ring
gear and that is spline-fitted movably in the rotation axis
direction and relatively non-rotatably to the outer circumferential
side of the cylindrical member to move in the rotation axis
direction together with the connecting/disconnecting sleeve, and
the relative rotation between the first connecting/disconnecting
teeth and the second connecting/disconnecting teeth is reduced
through the frictional engagement between the first tapered
friction engagement surface and the second tapered friction
engagement surface at the second non-meshing position. As a result,
since the relative rotation between the ring gear and the
connecting/disconnecting sleeve is reduced before the meshing of
the second connecting/disconnecting teeth with the first
connecting/disconnecting teeth, gear noise and wear are preferably
suppressed between the first connecting/disconnecting teeth and the
second connecting/disconnecting teeth.
According to the vehicle driving-force distributing device recited
in the sixth aspect of the invention, the connecting/disconnecting
mechanism includes the actuator and the latching mechanism, and the
latching mechanism includes the first piston reciprocated in the
rotation axis direction in accordance with the on/off operation of
the actuator, the second piston disposed movably in the rotation
axis direction on the outer circumferential side of the cylindrical
member and driven by the first piston in the rotation axis
direction to press the friction engagement member and the
connecting/disconnecting sleeve, the spring urging the second
piston in the backward movement direction, and the holder latching
the second piston against the urging force of the spring in
accordance with reciprocation of the first piston and unlatching
the second piston in accordance with reciprocation of the first
piston to allow the second piston to move backward in accordance
with the urging force of the spring. As a result, it is only
necessary to drive the actuator for a relatively short time for
moving the connecting/disconnecting sleeve backward and forward, so
that power consumption can be reduced.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is a skeleton diagram for generally explaining a
configuration of a four-wheel-drive vehicle 10 to which the present
invention is preferably applied.
FIG. 2 is a cross-sectional view for explaining a configuration of
a rear-wheel driving-force distributing device disposed on the
four-wheel-drive vehicle of FIG. 1.
FIGS. 3A to 3E are a schematic views for explaining an operation
principle of a latching mechanism included in the rear-wheel
driving-force distributing device of FIG. 2.
FIG. 4 is an enlarged cross-sectional view for explaining a
synchronizing mechanism of the rear-wheel driving-force
distributing device of FIG. 2 in detail.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
In an embodiment of the present invention, a driving-force
distributing device of the present invention is applicable not only
to a vehicle including an engine as a drive power source but also
to a vehicle using an electric motor as a drive power source.
In an embodiment of the present invention, the driving-force
distributing device of the present invention is suitably used for
distributing a driving force to a pair of left and right rear
wheels of a vehicle.
Embodiment of the present invention will now be described in detail
with reference to the drawings. In the following example, the
figures are simplified or deformed as needed and portions are not
necessarily precisely drawn in terms of dimension ratio, shape,
etc.
Embodiment
FIG. 1 is a skeleton diagram for generally explaining a
configuration of a four-wheel-drive vehicle 10 to which the present
invention is preferably applied. In FIG. 1, the four-wheel-drive
vehicle 10 includes a four-wheel-drive device of an FF type having
a first power transmission path transmitting a driving force of an
engine 12 serving as a drive power source to a pair of left and
right front wheels 14L, 14R (also referred to as "front wheels 14")
corresponding to main drive wheels and a second power transmission
path transmitting the driving force of the engine 12 to a pair of
left and right rear wheels 16L, 16R (also referred to as "rear
wheels 16") corresponding to auxiliary drive wheels.
In a two-wheel-drive state of the four-wheel-drive vehicle 10, the
driving force transmitted from the engine 12 via an automatic
transmission 18 is transmitted through a front-wheel driving-force
distributing device 20 and left and right axles 22L, 22R to the
left and right front wheels 14L, 14R. In this two-wheel-drive
state, at least a first clutch 24 is released, and no driving force
is transmitted to a transfer 26 as well as a propeller shaft 28, a
rear-wheel driving-force distributing device (vehicle driving-force
distributing device) 30 and the rear wheels 16L, 16R. However, in a
four-wheel-drive state, the first clutch 24 and a second clutch
(connecting/disconnecting mechanism) 32 are both engaged, and the
driving force from the engine 12 is transmitted to the transfer 26
as well as the propeller shaft 28, the rear-wheel driving-force
distributing device 30 and the rear wheels 16L, 16R.
In the two-wheel-drive state and the four-wheel-drive state of the
four-wheel-drive vehicle 10, the front-wheel driving-force
distributing device 20 distributes the driving force transmitted
from the engine 12 via a first differential device 34 to the front
wheels (drive wheels) 14L, 14R. In the four-wheel-drive state of
the four-wheel-drive vehicle 10, the rear-wheel driving-force
distributing device 30 distributes the driving force transmitted
from the engine 12 via a second differential device (differential
device) 36 to the rear wheels (drive wheels) 16L, 16R. Although not
shown in FIG. 1, a torque converter, a fluid coupling, or a clutch
is disposed as a hydraulic power transmission between the engine 12
and the automatic transmission 18.
The front-wheel driving-force distributing device 20 includes, in a
rotatable manner around a first rotation axis C1, the first
differential device 34 having a ring gear 34r meshed with an output
gear 18a of the automatic transmission 18 and a differential case
34c integrally fixed to the ring gear 34r and having a pair of
differential gears 34s assembled therein such that the first
differential device 34 transmits the driving force from the engine
12 to the left and right axles 22L, 22R of the front wheels 14L,
14R while allowing a differential rotation thereof. The
differential case 34c is provided with inner-circumferential
fitting teeth 34a fitted to outer-circumferential fitting teeth 38a
formed on an axial end portion on the first differential device 34
side of a first rotating member 38 disposed in the transfer 26. As
a result, a portion of the driving force transmitted from the
engine 12 to the front wheels 14L, 14R is transmitted from the
differential case 34c to the transfer 26.
As shown in FIG. 1, the transfer 26 includes the first rotating
member 38 provided with the outer-circumferential fitting teeth 38a
and a second rotating member 40 having an integrally-formed ring
gear 40r for transmitting the driving force toward the rear wheels
16L, 16R. In the transfer 26, a power transmission path between the
first rotating member 38 and the second rotating member 40 is
selectively connected/disconnected (i.e., in power transmittable
state/in cut-off state) by the first clutch 24 made up of a
meshing-type dog clutch.
As shown in FIG. 1, the first rotating member 38 is a cylindrical
member an inner circumferential side of which the axle 22R
penetrates and is disposed concentrically with the axle 22R and the
second rotating member 40, i.e., rotatably around the first
rotation axis C1. First clutch teeth 38b constituting a portion of
the first clutch 24 are integrally formed on an axial end portion
of the first rotating member 38 on the side opposite to the first
differential device 34.
As shown in FIG. 1, the second rotating member 40 is a cylindrical
member an inner circumferential side of which the axle 22R
penetrates and the first rotating member 38 on the inner
circumferential side and is disposed concentrically with the axle
22R and the first rotating member 38, i.e., rotatably around the
first rotation axis C1. The ring gear 40r meshed with a driven
pinion 42 is formed integrally with an axial end portion of the
second rotating member 40 on the first differential device 34 side,
and second clutch teeth 40a constituting a portion of the first
clutch 24 are integrally formed with an axial end portion of the
second rotating member 40 on the side opposite to the first
differential device 34. The driven pinion 42 is coupled to an end
portion of the propeller shaft 28 on the front wheel 14 side, and a
drive pinion 46 is disposed, via a control coupling 44 capable of
controlling a transmission torque by an electronic control device
not shown, at an end portion of the propeller shaft 28 on the rear
wheel 16 side.
The first clutch 24 is a meshing clutch for
connecting/disconnecting between the first rotating member 38 and
the second rotating member 40 and is a meshing-type dog clutch
including a sleeve 48 provided with inner circumferential teeth 48a
constantly meshed with the first clutch teeth 38b formed on the
first rotating member 38 while relatively movably in the first
rotation axis C1 direction and capable of meshing with the second
clutch teeth 40a formed on the second rotating member 40 through
the movement in the first rotation axis C1 direction, and a first
actuator 50 driving the sleeve 48 between a first non-meshing
position and a first meshing position in the first rotation axis C1
direction. The first meshing position is a position to which the
sleeve 48 moves in the first rotation axis C1 direction so that the
inner circumferential teeth 48a of the sleeve 48 are meshed with
the second clutch teeth 40a of the second rotating member 40, and
the first non-meshing position is a position to which the sleeve 48
moves in the first rotation axis C1 direction so that the inner
circumferential teeth 48a of the sleeve 48 are not meshed with the
second clutch teeth 40a of the second rotating member 40. The first
actuator 50 is made up of an actuator electrically controllable by
using an electromagnet, for example. The first clutch 24 preferably
includes a synchronizing mechanism 52 reducing a difference in
relative rotation between the sleeve 48 and the second rotating
member 40 when the inner circumferential teeth 48a of the sleeve 48
are meshed with the second clutch teeth 40a of the second rotating
member 40. FIG. 1 shows a state in which the first clutch 24 is
released.
As shown in FIGS. 1 and 2, the rear-wheel driving-force
distributing device 30 includes the second differential device
(differential device) 36 having a differential case 36c in which a
pair of differential gears 36sa, 36sb is assembled, and a
differential carrier 54 that is a non-rotating member fixed to a
vehicle body not shown in a state of housing the second
differential device 36 and that supports the differential case 36c
via bearings 64 and 66 rotatably around a second rotation axis
(rotation axis) C2 and immovably in a second rotation axis C2
direction. To one differential gear 36sa of the paired differential
gears 36sa, 36sb, an axle 72L is coupled by spline fitting via an
intermediate shaft 74 described later, and an axle 72R is coupled
by spline fitting to the other differential gear 36sb (see FIG.
1).
The rear-wheel driving-force distributing device 30 includes: a
second clutch (connecting/disconnecting mechanism) 32 that includes
a cylindrical ring gear 56 provided with inner-circumferential
connecting/disconnecting teeth (first connecting/disconnecting
teeth) 56a on the inner circumferential side, a cylindrical member
58 having cylindrical shape and arranged concentrically with the
differential gears 36sa and 36sb and coupled relatively
non-rotatably to a shaft insertion portion 36a at one end portion
of the differential case 36c and a connecting/disconnecting sleeve
60 having outer-circumferential connecting/disconnecting teeth
(second connecting/disconnecting teeth) 60a on the outer
circumferential side and spline-fitted movably in the second
rotation axis C2 direction and relatively non-rotatably to the
outer circumferential side of the shaft insertion portion 36a and
that connects and disconnects a power transmission path between the
ring gear 56 and the differential case 36c by moving the
connecting/disconnecting sleeve 60 in the second rotation axis C2
direction between a second meshing position (meshing position) at
which the outer-circumferential connecting/disconnecting teeth 60a
are meshed with the inner-circumferential connecting/disconnecting
teeth 56a and a second non-meshing position (non-meshing position)
at which the outer-circumferential connecting/disconnecting teeth
60a are not meshed with the inner-circumferential
connecting/disconnecting teeth 56a; and a synchronizing mechanism
112 (see FIG. 2) disposed between the ring gear 56 and the
cylindrical member 58 and reducing relative rotation between the
outer-circumferential connecting/disconnecting teeth 60a and the
inner-circumferential connecting/disconnecting teeth 56a
immediately before the outer-circumferential
connecting/disconnecting teeth 60a are meshed with the
inner-circumferential connecting/disconnecting teeth 56a.
Additionally, the rear-wheel driving-force distributing device 30
is provided with the intermediate shaft 74 inserted through the
cylindrical member 58 and the shaft insertion portion 36a of the
differential case 34c and having an end portion (one end portion)
on the second differential device 36 side coupled to the
differential gear 36sa and an end portion (the other end portion)
on the side opposite to the second differential device 36 side
coupled to the axle (drive shaft) 72L (see FIG. 1) in a power
transmittable manner.
As shown in FIG. 2, the differential case 36c integrally includes a
main body portion 36d housing the pair of the differential gears
36sa, 36sb and a pair of pinion gears 36b meshed with the pair of
the differential gears 36sa, 36sb, the shaft insertion portion 36a
cylindrically projected from an end portion of the main body
portion 36d on the rear wheel 16L side toward the rear wheel 16L,
and a projection portion 36e cylindrically projected from an end
portion of the main body portion 36d on the rear wheel 16R side
toward the rear wheel 16R. The differential case 36c integrally
includes a columnar pinion shaft 36f (see FIG. 2) rotatably
supporting the pair of the pinion gears 36b.
Inner-circumferential spline teeth 36g are formed on the
differential gear 36sa in the differential case 36c, and outer
circumferential spline teeth 74a formed on an end portion of the
intermediate shaft 74 on the second differential device 36 side are
fitted, i.e., spline-fitted, to the inner-circumferential spline
teeth 36g of the differential gear 36sa. Inner-circumferential
spline teeth 74b are formed on an inner circumference side of an
end portion of the intermediate shaft 74 on the side opposite to
the second differential device 36 side, and an end portion of the
axle 72L on the second differential device 36 side (see FIG. 1) are
spline-fitted to the inner-circumferential spline teeth 74b of the
intermediate shaft 74.
The ring gear 56 is a cylindrical member supported by the
differential carrier 54 via a bearing 78 rotatably around the
second rotation axis C2 and immovably in the second rotation axis
C2 direction and meshed with the drive pinion 46 and has an inner
circumferential surface with the inner-circumferential
connecting/disconnecting teeth 56a formed at an end portion on the
second differential device (differential device) 36 side. The ring
gear 56 is, for example, a bevel gear formed as a hypoid gear, and
a shaft portion 56b is formed into a substantially cylindrical
shape projected from an inner circumferential portion of the ring
gear 56 toward the rear wheel 16L. The cylindrical ring gear 56 is
supported in a cantilever manner rotatably around the second
rotation axis C2 since the shaft portion 56b of the ring gear 56 is
supported by the differential carrier 54 via the bearing 78. The
bearing 78 is provided with a flange portion 80a annularly
projecting from an outer ring 80 of the bearing 78 to the outer
circumferential side, and the flange portion 80a is fastened to the
differential carrier 54 by a bolt 81 (see FIG. 2) so that the
bearing 78 is fixed to the differential carrier 54.
The shaft insertion portion 36a is a cylindrical portion projected
in the second rotation axis C2 direction from an end portion (one
end portion) of the differential case 36c on the rear wheel 16L
side. The cylindrical member 58 has an outer diameter and an inner
diameter equal to those of the shaft insertion portion 36a and is
abutted on an end surface of the shaft insertion portion 36a on the
rear wheel 16L side and relatively non-rotatably coupled in an
integrally lined-up state in the second rotation axis C2 direction
by a tubular coupling member 62 having a smaller diameter than the
shaft insertion portion 36a and interference-fitted or
spline-fitted into the cylindrical member 58 and the shaft
insertion portion 36a. The tubular coupling member 62 non-rotatably
couples the shaft insertion portion 36a and the cylindrical member
58 by, for example, spline fitting or press fitting of outer
circumferential spline teeth formed on an outer circumferential
surface thereof and inner-circumferential spline teeth formed on
inner circumferential surfaces of the shaft insertion portion 36a
and the cylindrical member 58. Although the cylindrical member 58
may be formed integrally with the shaft insertion portion 36a, the
cylindrical member 58 is formed separately from the shaft insertion
portion 36a so that easiness of assembly is enhanced.
The connecting/disconnecting sleeve 60 has the outer
circumferential contact teeth 60a formed on the outer
circumferential surface, i.e., the outer circumferential side
thereof, and inner-circumferential spline teeth 60b formed on the
inner circumferential surface, i.e., the inner circumferential side
thereof, and is disposed on the outer circumferential side of the
shaft insertion portion 36a movably in the second rotation axis C2
direction and relatively non-rotatably with respect to the shaft
insertion portion 36a due to constant spline fitting of the
inner-circumferential spline teeth 60b to outer-circumferential
spline teeth 36aa formed on an outer circumferential surface of the
shaft insertion portion 36a. The connecting/disconnecting sleeve 60
has an annular shape or a short cylindrical shape, and a pitch
circle of the outer-circumferential connecting/disconnecting teeth
60a formed on the outer circumferential surface having a relatively
large diameter has a larger diameter than a pitch circle of the
inner-circumferential spline teeth 60b formed on the inner
circumferential surface having a relatively small diameter. The
outer-circumferential connecting/disconnecting teeth 60a disposed
on the outer circumferential side of the connecting/disconnecting
sleeve 60 have a face width longer than a movement stroke ST due to
driving of a ball cam 106 described later and smaller than that of
the inner-circumferential spline teeth 60b (see FIG. 1).
The second clutch 32 functions as a connecting/disconnecting
mechanism connecting and disconnecting the power transmission path
between the ring gear 56 and the differential case 36c by moving
the connecting/disconnecting sleeve 60 in the second rotation axis
C2 direction between the second meshing position (meshing position)
at which the outer-circumferential connecting/disconnecting teeth
60a of the connecting/disconnecting sleeve 60 are meshed with the
inner-circumferential connecting/disconnecting teeth 56a of the
ring gear 56 and the second non-meshing position (non-meshing
position) at which the outer-circumferential
connecting/disconnecting teeth 60a of the connecting/disconnecting
sleeve 60 are not meshed with the inner-circumferential
connecting/disconnecting teeth 56a of the ring gear 56.
As shown in FIG. 2, the second clutch 32 functioning as the
connecting/disconnecting mechanism includes: a control clutch 96
activated by an electromagnet 94 functioning as an actuator; a
ratchet mechanism, i.e., latching mechanism 92, moving the
connecting/disconnecting sleeve 60 in the second rotation axis C2
direction to move the connecting/disconnecting sleeve 60 between
the second meshing position and the second non-meshing position;
and the synchronizing mechanism 112 reducing a difference in
relative rotation between the inner-circumferential
connecting/disconnecting teeth 56a and the outer-circumferential
connecting/disconnecting teeth 60a before meshing of the
outer-circumferential connecting/disconnecting teeth 60a disposed
on the outer circumferential side of the connecting/disconnecting
sleeve 60 with the inner-circumferential connecting/disconnecting
teeth 56a disposed on the inner circumferential side of the ring
gear 56.
As shown in FIG. 2, the electromagnet 94 of annular shape acting as
the actuator is assembled in the differential carrier 54 along with
an annular movable piece 116 adjacent to the electromagnet 94 via
an annular friction plate 114 and magnetically attractable to the
electromagnet 94. The friction plate 114 is relatively
non-rotatably coupled to a second cam 102 on its outer
circumferential side while the second cam 102 is disposed
relatively rotatably around the second rotation axis C2 with
respect to the cylindrical member 58. The control clutch 96 is made
up of the electromagnet 94, the movable piece 116, and the friction
plate 114, and when the movable piece 116 is attracted due to the
activation of the electromagnet 94, a rotation braking torque is
transmitted to the friction plate 114 and the second cam 102
relatively non-rotatably coupled thereto.
As shown in FIG. 2, the latching mechanism 92 includes a first
spring 90, a second piston 98, the ball cam 106, a second spring
108 (spring), and a holder 110. The second piston 98 is disposed on
the outer circumferential side of the cylindrical member 58
rotatably around the second rotation axis C2 and movably in the
second rotation axis C2 direction. The second piston 98 presses the
connecting/disconnecting sleeve 60 via a friction engagement member
120 described later and moves the connecting/disconnecting sleeve
60 to the second non-meshing position against the urging force of
the second spring 108.
The ball cam 106 has an annular-shaped pair of a first cam 100
(first piston) and a second cam 102 interposed between the second
piston 98 and the bearing 64 to overlap with the second piston 98
and the bearing 64 in the second rotation axis C2 direction and
relatively rotated around the second rotation axis C2 due to the
activation of the electromagnet 94, and multiple (e.g., three)
spherical rolling elements 104 put between a pair of mutually
facing groove-shaped cam surfaces 100b, 102b each having a depth
varying along longitudinal (circumferential) direction and formed
at multiple positions (e.g., three positions) in a circumferential
direction in the first cam 100 and the second cam 102, and when the
pair of the first cam 100 and the second cam 102 is relatively
rotated around the second rotation axis C2, the first cam 100 and
the second cam 102 are separated in the second rotation axis C2
direction, and the first cam 100 is moved toward the second piston
98. Although not shown, an inner circumferential surface of the
first cam 100 is provided with inner circumferential meshing teeth
meshed relatively non-rotatably and movably in the second rotation
axis C2 direction with outer-circumferential spline teeth formed on
the cylindrical member 58. When the cylindrical member 58 rotates,
for example, around the second rotation axis C2, the first cam 100
also rotates about the second rotation axis C2 and, for example,
when the electromagnet 94 acting as the actuator is not operating,
the second cam 102 rotates integrally with the first cam 100 via
the spherical rolling element 104.
The first spring 90 is interposed between the first cam 100 and the
holder 110 in a preloaded state and urges the first cam 100 toward
the second cam 102. The second spring 108 urges the second piston
98 to the side away from the second differential device 36 in the
second rotation axis C2 direction via the connecting/disconnecting
sleeve 60 and the friction engagement member 120. The holder 110
has latching teeth 110a (see FIG. 3) and is disposed relatively
non-rotatably around the second rotation axis C2 and immovably in
the second rotation axis C2 direction with respect to the
cylindrical member 58 to latch the second piston 98 with the
latching teeth 110a.
In the latching mechanism 92 configured as described above, for
example, when the movable piece 116 is attracted to the
electromagnet 94 due to activation of the electromagnet 94 acting
as the actuator while the vehicle 10 is running and the cylindrical
member 58 is rotating around the second rotation axis C2, the
rotation braking torque is transmitted to the friction plate 114
and the second cam 102 relatively non-rotatably coupled thereto.
This rotation braking torque causes relative rotation between the
first cam 100 relatively non-rotatable around the second rotation
axis C2 with respect to the cylindrical member 58 and the second
cam 102 relatively rotatable around the second rotation axis C2
with respect to the cylindrical member 58, so that the first cam
100 moves forward via the spherical rolling element 104 toward the
second piston 98 against the urging force of the first spring 90 in
the second rotation axis C2 direction while the second piston 98 is
pressed by the first cam 100. When the electromagnet 94 is put into
a deactivated state, the first cam 100 is separated from the second
piston 98 by the urging force of the first spring 90, and the first
cam 100 moves backward in the direction toward the second cam 102
due to the urging force of the first spring 90.
FIGS. 3A to 3E are a schematic views for explaining an operation
principle of the latching mechanism 92 and shows a state in which
the annular second piston 98, a pressing portion 100c of the
annular first cam 100, and the annular holder 110 are each
developed. As shown in FIGS. 3A to 3E, the annular second piston 98
is provided with a projection 98a projected toward the holder 110.
The annular holder 110 has the latching teeth 110a periodically
formed into a saw tooth shape and arranged in the circumferential
direction for latching the projection 98a of the second piston 98,
and the holder 110 is disposed at a fixed position on the
cylindrical member 58.
The pressing portion 100c of the annular first cam 100 has
receiving teeth 100d periodically formed into the saw tooth shape
similar to the latching teeth 110a of the holder 110 and arranged
in the circumferential direction in a shape shifted by a
predetermined phase in the circumferential direction to receive the
projection 98a of the second piston 98. The pressing portion 100c
of the annular first cam 100 is disposed relatively non-rotatably
and movably in the second rotation axis C2 direction with respect
to the holder 110, and can move the second piston 98 by one stroke
of the ball cam 106 against the urging forces of the first spring
90 and the second spring 108. Slopes at tips of the receiving teeth
100d of the pressing portion 100c of the first cam 100 and the
latching teeth 110a of the holder 110 are respectively provided
with stoppers 100e and 110b stopping a slip of the projection 98a
of the second piston 98.
FIGS. 3A and 3E show the disconnection sleeve 60 positioned at the
second meshing position. As shown in FIGS. 3A and 3E, while the
projection 98a projected from the second piston 98 is positioned at
a position unlatched from the latching teeth 110a of the holder
110, the connecting/disconnecting sleeve 60 is positioned at the
second meshing position in accordance with the urging force of the
second spring 108.
FIG. 3B shows a state in which the second piston 98 is moved from
the base position thereof against the urging forces of the first
spring 90 and the second spring 108 by the movement stroke ST due
to driving of the ball cam 106 resulting from energization of the
electromagnet 94 acting as the actuator. In this process, the
second piston 98 is moved by the pressing portion 100c of the first
cam 100 and is separated from the holder 110, and the second piston
98 slips down a slope 100f of the pressing portion 100c in the
first cam 100. A dashed-dotted line shown in FIG. 3B indicates the
base position of the pressing portion 100c in the first cam 100 of
FIG. 3A for explaining the movement stroke ST.
In a state shown in FIG. 3C, due to non-driving of the ball cam 106
resulting from non-energization of the electromagnet 94, the
pressing portion 100c of the first cam 100 is returned by the
movement stroke ST in accordance with the urging forces of the
first return spring 90 and is positioned at the base position. In
this process, the second piston 98 is latched on the latching teeth
110a of the holder 110 against the urging force of the second
spring 108, and the connecting/disconnecting sleeve 60 is
positioned at the second non-meshing position.
In a state shown in FIG. 3D, since the ball cam 106 is driven due
to driving of the ball cam 106 resulting from energization of the
electromagnet 94, the pressing portion 100c of the first cam 100 is
moved again by the movement stroke ST from the base position
against the urging forces of the first spring 90 and the second
spring 108. In this process, the second piston 98 is further moved
toward the second differential device 36, and a rotation speed of
the ring gear 56 and a rotation speed of the first
connecting/disconnecting sleeve 60 are synchronized by the
synchronizing mechanism 112.
Subsequently, as shown in FIG. 3E, as the pressing portion 100c of
the first cam 100 is returned toward the base position in
accordance with the urging forces of the first spring 90 and the
second spring 108 due to non-driving of the ball cam 106 resulting
from non-energization of the electromagnet 94, the second piston 98
is unlatched from the latching teeth 110a of the holder 110 and
returned to the position unlatched from the latching teeth 110a of
the holder 110 in accordance with the urging force of the second
spring 108, so that the connecting/disconnecting sleeve 60 is
positioned at the second meshing position.
As a result, the latching mechanism 92 forwards the second piston
98 in the circumferential direction through the reciprocation of
the first cam 100 in the ball cam 106 so as to move the
connecting/disconnecting sleeve 60 toward the second non-meshing
position and the second meshing position. Specifically, when the
second piston 98 is reciprocated once by the first cam 100, the
connecting/disconnecting sleeve 60 is positioned at the second
non-meshing position. When the second piston 98 reciprocates twice
by the first cam 100, i.e., when the second piston 98 is further
reciprocated once by the first cam 100 while the
connecting/disconnecting sleeve 60 is at the second non-meshing
position, the second piston 98 is unlatched from the latching teeth
110a of the holder 110 so that the connecting/disconnecting sleeve
60 is positioned at the second meshing position by the urging force
of the second spring 108.
In the four-wheel-drive vehicle 10 configured as described above,
for example, when a two-wheel-drive running mode is selected by the
electronic control device not shown in the four-wheel-drive state
in which both the first clutch 24 and the second clutch 32 are
engaged, the first actuator 50 moves the sleeve 48 to the first
non-meshing position to release the first clutch 24, while the
deactivated state of the electromagnet 94 brings the
connecting/disconnecting sleeve 60 to move to the second
non-meshing position in the rear-wheel driving-force distributing
device 30 to release the second clutch 32, resulting in the
two-wheel-drive state in which the driving force from the engine 12
is transmitted only to the front wheels 14 that are main drive
wheels.
When a four-wheel-drive running mode is selected by the electronic
control device not shown in the two-wheel-drive state in which the
first clutch 24 and the second clutch 32 are both released, i.e.,
in a disconnected state in which the power transmission path
between the engine 12 and the propeller shaft 28 and the power
transmission path between the rear wheels 16 and the propeller
shaft 28 are respectively disconnected, for example, the first
actuator 50 moves the sleeve 48 to the first meshing position to
engage the first clutch 24, while an activated state of the
electromagnet 94 brings the connecting/disconnecting sleeve 60 to
move to the second meshing position after the engagement of the
first clutch 24 to engage the second clutch 32, thereby canceling
the disconnected state.
As shown in detail in FIG. 4, the synchronizing mechanism 112
includes the friction engagement member 120 that has on the outer
circumferential side a second tapered friction engagement surface
120a frictionally engageable with a first tapered friction
engagement surface 56c formed on an inner circumferential surface
of the ring gear 56 and that is spline-fitted movably in the second
rotation axis C2 direction and relatively non-rotatably to the
outer circumferential side of the cylindrical member 58 to move in
the second rotation axis C2 direction together with the
connecting/disconnecting sleeve 60, and reduces the relative
rotation between the inner-circumferential connecting/disconnecting
teeth 56a of the ring gear 56 and the outer-circumferential
connecting/disconnecting teeth 60a of the connecting/disconnecting
sleeve 60 before the meshing thereof through the frictional
engagement between the first tapered friction engagement surface
56c and the second tapered friction engagement surface 120a at the
second non-meshing position. The friction engagement member 120 is
disposed between the second piston 98 and the
connecting/disconnecting sleeve 60 and is pressed by the second
piston 98 to reciprocate together with the second piston 98.
As described above, the driving-force distributing device 30 for
the rear wheels of this example includes: the inner-circumferential
connecting/disconnecting teeth 56a disposed on the inner
circumferential side of the ring gear 56; the second clutch
(connecting/disconnecting mechanism) 32 that includes the
cylindrical member 58 arranged concentrically with the differential
gears 36sa, 36sb and coupled relatively non-rotatably to the shaft
insertion portion 36a at one end portion of the differential case
36c and the connecting/disconnecting sleeve 60 having the
outer-circumferential connecting/disconnecting teeth 60a on the
outer circumferential side and spline-fitted movably in the second
rotation axis C2 direction and relatively non-rotatably to the
outer circumferential side of the shaft insertion portion 36a and
that connects and disconnects the power transmission path between
the ring gear 56 and the differential case 36c by moving the
connecting/disconnecting sleeve 60 in the second rotation axis C2
direction between the second meshing position at which the
outer-circumferential connecting/disconnecting teeth 60a are meshed
with the inner-circumferential connecting/disconnecting teeth 56a
and the second non-meshing position at which the
outer-circumferential connecting/disconnecting teeth 60a are not
meshed with the inner-circumferential connecting/disconnecting
teeth 56a; and the synchronizing mechanism 112 disposed between the
ring gear 56 and the cylindrical member 58 and reducing the
relative rotation between the outer-circumferential
connecting/disconnecting teeth 60a and the inner-circumferential
connecting/disconnecting teeth 56a, and therefore, the
outer-circumferential connecting/disconnecting teeth 60a disposed
on the outer circumferential side of the connecting/disconnecting
sleeve 60 have a larger diameter than the inner-circumferential
spline teeth 60b on the inner circumferential side of the
connecting/disconnecting sleeve 60.
Therefore, the outer-circumferential connecting/disconnecting teeth
60a and the inner-circumferential connecting/disconnecting teeth
56a meshed therewith can be improved in strength, and thus, even if
the space is limited due to inclusion of the synchronizing
mechanism 112, the driving-force distributing device 30 can be made
advantageous in terms of the strength of the inner-circumferential
connecting/disconnecting teeth 56a and the outer-circumferential
connecting/disconnecting teeth 60a, so that the
inner-circumferential connecting/disconnecting teeth 56a and the
outer-circumferential connecting/disconnecting teeth 60a can be
enhanced in durability. Additionally, the synchronizing mechanism
112 is disposed in a space between the ring gear 56 and the
cylindrical member 58 so that the driving force is transmitted
between the connecting/disconnecting sleeve 60 and the shaft
insertion portion 36a, and therefore, for example, as compared to
the case that both the cylindrical member 58 and the shaft
insertion portion 36a must be enhanced in strength if the driving
force is transmitted between the connecting/disconnecting sleeve 60
and the cylindrical member 58, the strength is advantageously
enhanced by increasing only the strength of the shaft insertion
portion 36a.
According to the driving-force distributing device 30 of this
example, the connecting/disconnecting sleeve 60 has the
inner-circumferential spline teeth 60b for spline fitting to the
outer circumferential side of the shaft insertion portion 36a, and
the pitch circle of the outer-circumferential
connecting/disconnecting teeth 60a disposed on the outer
circumferential side of the connecting/disconnecting sleeve 60 has
a larger diameter than the pitch circle of the
inner-circumferential spline teeth 60b. As a result, the
outer-circumferential connecting/disconnecting teeth 60a and the
inner-circumferential connecting/disconnecting teeth 56a meshed
therewith can be improved in strength, and even if the space is
limited due to disposition of the synchronizing mechanism 112, the
driving-force distributing device 30 can be made advantageous in
terms of the strength of the outer-circumferential
connecting/disconnecting teeth 60a and the inner-circumferential
connecting/disconnecting teeth 56a meshed therewith.
According to the driving-force distributing device 30 of this
example, the outer-circumferential connecting/disconnecting teeth
60a disposed on the outer circumferential side of the
connecting/disconnecting sleeve 60 have a face width smaller than
the face width of the inner-circumferential spline teeth 60b
disposed on the inner circumferential side of the
connecting/disconnecting sleeve 60. As a result, the reciprocating
stroke of the connecting/disconnecting sleeve 60 can be reduced.
The reciprocating stroke can be reduced in the ball cam 106 of the
latching mechanism 92, and the latching mechanism 92 can be made
smaller in the dimension in the second rotation axis C2 direction.
Therefore, the driving-force distributing device 30 can be made
smaller in the dimension in the second rotation axis C2
direction.
According to the driving-force distributing device 30 of this
example, the shaft insertion portion 36a and the cylindrical member
58 have the outer and inner diameters equal to each other, and the
shaft insertion portion 36a and the cylindrical member 58 are lined
up in the second rotation axis C2 direction and relatively
non-rotatably coupled to each other by the tubular coupling member
62 having a smaller diameter than the outer diameter of the shaft
insertion portion 36a and the cylindrical member 58 and fitted into
the shaft insertion portion 36a and the cylindrical member 58. As a
result, the radial dimension of the driving-force distributing
device 30 is further reduced, which advantageously enhance the
easiness of assembly.
According to the driving-force distributing device 30 of this
example, the synchronizing mechanism 112 includes the friction
engagement member 120 that has on the outer circumferential side
the second tapered friction engagement surface 120a frictionally
engageable with the first tapered friction engagement surface 56c
formed on the inner circumferential surface of the ring gear 56 and
that is spline-fitted movably in the second rotation axis C2
direction and relatively non-rotatably to the outer circumferential
side of the cylindrical member 58 to move in the second rotation
axis C2 direction together with the connecting/disconnecting sleeve
60, and the relative rotation between the inner-circumferential
connecting/disconnecting teeth 56a and the outer-circumferential
connecting/disconnecting teeth 60a is reduced through the
frictional engagement between the first tapered friction engagement
surface 56c and the second tapered friction engagement surface 120a
at the second non-meshing position. As a result, since the relative
rotation between the ring gear 56 and the connecting/disconnecting
sleeve 60 is reduced before the meshing of the second
connecting/disconnecting teeth 60a with the first
connecting/disconnecting teeth 56a, gear noise and wear are
preferably suppressed between the first connecting/disconnecting
teeth 56a and the second connecting/disconnecting teeth 60a.
According to the rear-wheel driving-force distributing device 30 of
this example, the second clutch (connecting/disconnecting
mechanism) 32 includes the electromagnet (actuator) 94 and the
latching mechanism 92, and the latching mechanism 92 includes the
first cam (first piston) 100 reciprocated in the second rotation
axis C2 direction in accordance with an on/off operation of the
electromagnet 94, the second piston 98 disposed movably in the
second rotation axis C2 direction on the outer circumferential side
of the cylindrical member 58 and driven by the first cam (first
piston) 100 in the second rotation axis C2 direction to press the
friction engagement member 120 and the connecting/disconnecting
sleeve 60, the second spring (spring) 108 urging the second piston
98 in the backward movement direction, and the holder 110 latching
the second piston 98 against the urging force of the second spring
108 in accordance with reciprocation of the first cam 100 and
unlatching the second piston 98 in accordance with reciprocation of
the first cam 100 to allow the second piston 98 to move backward in
accordance with the urging force of the second spring 108. As a
result, it is only necessary to drive the electromagnet 94 for a
relatively short time for moving the connecting/disconnecting
sleeve 60 backward and forward, so that power consumption can be
reduced.
Although the embodiment of the present invention has been described
in detail with reference to the drawings, the present invention is
also applicable to other forms.
For example, although the latching teeth 110a having one stage is
formed on the holder 110 in the embodiment described above,
latching teeth having two or more stages, i.e., latching teeth
having multiple stages, may be formed.
In the embodiment described above, the rear-wheel driving-force
distributing device 30 distributes the driving force transmitted
from the engine 12 through the second differential device 36 to the
rear wheels 16L, 16R in the four-wheel-drive state of the
four-wheel-drive vehicle 10; however, for example, the
configuration of the rear-wheel driving-force distributing device
30 may be applied to a front-wheel driving-force distributing
device distributing the driving force transmitted from the engine
12 to the front wheels 14L, 14R in the four-wheel-drive state and
the two-wheel-drive state of the four-wheel-drive vehicle 10.
Although the control clutch 96 of the embodiment described above
includes the electromagnet 94 as the actuator, the actuator may be
of another type made of a shape memory alloy, piezoelectric
ceramics, etc.
The above description is merely an embodiment and the present
invention can be implemented in variously modified and improved
forms based on the knowledge of those skilled in the art.
REFERENCE SIGNS LIST
12: Engine (Drive power source)
16L, 16R: Rear wheels (Drive wheels)
30: Rear-wheel driving-force distributing device (Vehicle
driving-force distributing device)
32: Second clutch (Connecting/disconnecting mechanism)
36: Second differential device (Differential device)
36a: Shaft insertion portion
36c: Differential case
36sa, 36sb: Differential gear
56: Ring gear
56a: Inner-circumferential connecting/disconnecting teeth (First
connecting/disconnecting teeth)
56c: First tapered friction engagement surface
58: Cylindrical member
60: Connecting/disconnecting sleeve
60a: Outer-circumferential connecting/disconnecting teeth (Second
connecting/disconnecting teeth)
60b: Inner-circumferential spline teeth
92: Latching mechanism
94: Electromagnet (Actuator)
98: Second piston
100: First cam (First piston)
102: Second cam
106: Ball cam
108: Second spring (Spring)
110: Holder
112: Synchronizing mechanism
120: First engagement member
120a: Second tapered friction engagement surface
C2: Second rotation axis (Rotation axis)
* * * * *